Dresden 2009 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 18: Spin Structures and Magnetic Phase Transitions

MA 18.7: Vortrag

Mittwoch, 25. März 2009, 11:45–12:00, HSZ 401

Chirality in Dy/Y Multilayer — •Dieter Lott¹, Sergey V. Grigoriev², Yury O. Chetverikov², and Andreas Schreyer¹ — ¹GKSS Forchungszentrum, 21502 Geesthacht — ²Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg 188300, Russia

Chirality plays a crucial role in a wide variety of disciplines from biology to chemistry and physics. However, in the field of magnetism it did not attract a lot of attention until recently, when it was demonstrated for the first time that a single layer of manganese on tungsten orders of a specific chirality. It was interpreted being caused by the Dzyaloshinskii-Moriya (DM) interaction which arises from spin-orbit interactions of electrons due to the breaking of the inversion symmetry at the interface. Here, we present studies using polarized neutron scattering on Dy/Y multilayer structures demonstrating that the magnetic system possess a coherent spin helix with a preferable chirality induced by the magnetic field [1]. The average chirality, being proportional to the difference in the left- and right-handed helix population numbers, is measured as a polarization-dependent asymmetric part of the magnetic neutron scattering. The magnetic field applied in the plane of the sample upon cooling below T_N is able to repopulate the otherwise equal population numbers for the left- and right-handed helixes. The experimental results strongly indicate that chirality observed here for the first time in a multilayer system is a more general phenomenon and may play an important role in future spintronic devices. [1] S.V. Grigoriev, Yu. O. Chetverikov, D. Lott, and A. Schreyer, Phys. Rev. Lett. 100, 197203 (2008).